Raytheon and the US Air Force have started flight testing of the Small Diameter Bomb II’s coordinated attack capability, which uses GPS and anti-jamming to attack static targets from at least 40 miles away.

Recent flight tests also employed the SDB II’s normal attack capability, which fires on fixed and moving targets using infrared imaging and millimetre-wave seeker modes, according to Raytheon.

“Most people would look at SDB II and say technologically, the most complicated subsystem to address from a design [and] development perspective is the tri-mode seeker,” Mike Jarrett, vice-president of air warfare systems for Raytheon said at the Farnborough air show on 11 July. “We have fully qualified that seeker and we’ve demonstrated it in multiple flight tests in all the modes of operation quite successfully.”

Raytheon has also corrected a cabling issue with SDB II, after the bomb failed to detonate in a live fire testing event last September. The programme is moving ahead and should achieve initial operational capability by 2018, Jarrett says.

“In a live fire test, you go through the forensic evidence, which the ordnance folks are very good in the development programme about retrieving hardware from a flight test,” Jarrett says. “[They] made a conclusion on the most likely cause and we’re moving on.”

Raytheon also completed design verification tests for its corrosive environment correction on the weapon. The company must still wait for a formal qualification, which will determine the lot 2 contract award. Raytheon expects to complete qualification within the third quarter of the calendar year, Jarrett says.

The SDB II will be fielded on the Lockheed Martin F-35's B and C variants, and weapon integration also will be completed on the US Air Force’s Boeing F-15E. The bomb could potentially later be fielded on the Boeing F/A-18, Lockheed AC-130, F-16, F-22 and F-35A, the Fairchild Republic A-10 and General Atomics Aeronautical Systems' MQ-9.

The standoff-range weapon persists through bad weather, which Raytheon has touted as an advantage over laser guidance systems, which can be degraded by fog and other adverse conditions. The bomb is also designed to identify and prosecute mobile targets in a shorter time.

Schedule delays have plagued the SDB II, including a shift in the required assets available (RAA) schedule that pushed back initial operational capability. Raytheon’s RAA date moved from March 2018 to July 2018 to allow for the live fire failure investigation and give more time for additional developing testing, a March selected acquisition report from the Department of Defense.

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